Attention has heretofore been paid to a semiconductor power device that is used mainly for systems, such as a motor control system and a power conversion system, in various power electronics fields. For example, an SiC semiconductor device is publicly known as this type of semiconductor power device (see Patent Literature 1, for example).
The semiconductor device of Patent Literature 1 includes an SiC substrate, an n type high-resistivity layer formed on the SiC substrate, a p well layer formed on the n type high-resistivity layer, an n+ emitter region formed at a surface part of the p well layer, a p+ contact region that passes through the n+ emitter region and reaches the p well layer, a trench that passes through the p well layer from a surface of the n+ emitter region and reaches the n type high-resistivity layer, a gate oxide film formed at an inner surface of the trench, and a polysilicon gate electrode embedded in the trench.